This invention relates to medical apparatus and methods used to deliver medication through or into bone and other hard tissue. In particular, this invention relates to a medication delivery apparatus with a hollow drill bit and a beveled tip with an extended open slot or an open notch or hole at the perforating end. The invention also relates to a method of delivering medication through the hollow drill bit into or through bone and/or other hard tissue after drilling without removing the drill bit.
Dentists often conduct local anesthesia to patients to reduce pain during dental procedures. Many dentists and most patients, however, are dissatisfied with the results of traditional anesthetic injection techniques. Problems with administration of anesthetic in traditional injection technique include: slow onset of anesthesia after injection, the long duration and extent of postoperative numbness for patients, especially on children, and the occasional inability to achieve total anesthesia.
One prior art solution was the intraosseous injection technique developed in the early 1900""s. The intraosseous injection technique involves 3 simple steps. First, a dentist anesthetizes the gingival tissue topically over the target site of perforation (a point between the problem tooth and the adjacent tooth). Second, the dentist drills through the cortical plate of the jawbone to create a hole. Lastly, local anesthetic solution is injected into the cancellous bone through the hole by regular syringe and needle. The intraosseous injection technique eliminated many of the problems of the traditional injection. The anesthetic took effect quickly and effectively and caused little postoperative numbness. In addition, unlike other techniques, it worked well in almost all patients. However, the intraosseous injection technique had many problems in its early days, including the lack of tools designed for the technique. The technique also produced large holes causing significant bone and soft tissue trauma with increased risk of bone infection.
One prior art improvement of the intraosseous injection technique was developed in late 1980""s. It was the Stabident System, which involved the use of a small wire drill (diameter of 0.016 inch, equivalent to 27 gauge). The use of a small drill bit reduced tissue damage and the risk of infection.
In spite of these advantages, the Stabident System has several drawbacks. In particular, dentists were required to switch to a hypodermic needle to inject anesthetic once a hole was drilled with the small drill bit. To identify the location of the hole and aim a very small hypodermic needle through the hole is very difficult because the opening produced by the small drill bit is covered by gingival tissue. Another problem with the Stabident System is that the stainless steel drill bits were not properly tempered. As a result, the drill bits would occasionally wear out prematurely. Worn out drill bits generate excessive heat during use, which may cause heat damage to the surrounding bone tissue. In addition, excessive heat levels occasionally cause meltdown and detachment of the plastic hub attached to the drill bit. This can result in the detached drillhead being left inside the patient""s jawbone leading to further complications.
Rotary dental tools with hollow bits have been used in the past as a grinding tool. Such a tool has a low speed and a relatively large-diameter hollow bit for grinding bone while supplying water to the grinding area to lubricate and flush particles. However, this art does not disclose a means to supply anesthetic or medication to a tooth.
An improvement over these techniques was the subject of the U.S. Pat. No. 5,779,708, issued Jul. 14, 1998 and invented by the same inventor as the present invention. The ""708 patent relates to a small diameter hollow drill bit that has a removable stylet in place during drilling so that the bore of the drill bit does not become clogged with drilling debris. After the hole is drilled, the stylet is removed and the medication is injected through the hollow drill bit.
In order to meet these concerns, the present invention is directed to an intraosseous and/or hard tissue drug delivery system that provides an easily identified and accessible drug delivery passage for the operator, thereby, greatly reducing the technical difficulty and extending the potential applications of the intraosseous and/or hard tissue injection technique. In other words, this invention is a hard tissue and/or intraosseous drug delivery system that perforates the hard tissue and also provides a visible and uncovered drug delivery passage through the soft tissue.
The present invention is a medication delivery device that encompasses a hollow drill bit with an open slot that extends from a distal beveled tip toward the proximal end of the drill. This extended slot design allows the hollow drill to penetrate bone and/or other hard tissues without being clogged by the bone or hard tissue debris, as long as the overall length of the bevel and open slot is greater than the thickness of bone and/or hard tissue. After drilling into the bone or hard tissue, medication can be delivered through the hollow drill. The extended length of the open slot provides a clog-free passage for injection of the medication.
An alternative design of this invention is a hollow drill bit with an open notch (a small hole through the wall of the hollow drill) located proximal of the distal beveled tip. As long as the overall distance from the distal tip of the bevel to the open notch is greater than the thickness of cortical bone and/or hard tissue, the hollow drill will not be clogged by the debris from bone and/or hard tissue and medication can be injected into the site.
A feature of this invention is that the extended slot or open notch provides a longer open area of the lumen of the hollow drill than a hollow drill with a beveled tip. In the drilling process with traditional single or double beveled hollow drill, if the length of the bevel is close to or shorter than the thickness of the bone and/or hard tissue, the hollow drill (without a stylet) will be clogged by the debris after the beveled area has submerged into the bone before the drill tip has penetrated to the other side of the dense bone layer. A beveled drill bit with an extended slot, according to the present invention, can drill through the same bone and/or hard tissue without being clogged because the debris from the bone and/or hard tissue will only fill the lumen up to the same length as the thickness of the cortical bone and/or hard tissue. Therefore, the part of extended slot beyond the thickness of the cortical bone and/or hard tissue will stay open for the medication to flow through. With the alternative open notch design, the hollow drill can drill through the bone and/or hard tissue of a thickness less than the length from the drill tip to the distal edge (toward tip end) of the notch without being clogged. After the perforation and while keeping the hollow drill in place, the dentist or practitioner can deliver medication through the hollow drill by using a syringe type device with a hypodermic needle with an O.D. (outer diameter) smaller than the I.D. (inner diameter) of the hollow drill.
An advantage of the present invention is that it provides maximum simplicity and effectiveness to intraosseous drug delivery technology. This invention eliminates the need of a stylet for a hollow drill to prevent the hollow drill being clogged by the bone and/or hard tissue debris during the drilling process. It provides the solution to the current problems of intraosseous injection encountered by dentists in dental anesthesia heretofore. This invention also provides broader applicability of the intraosseous injection technique to dental anesthesia, dental medications and other potential medical applications.
In a preferred embodiment, the hollow drill bit of this medication device is a hypodermic tube having a sharpened point and an extended slot. An alternative structure arrangement is a hypodermic tube having a sharpened point and an open notch or hole through the wall of the hollow drill above (proximal to) the sharpened tip. The blunt end of the hollow drill is embedded in a hub shaped to fit into the chuck of a rotating tool.
The hollow drill bit is preferably sized at 24 G (gauge) so it will produce only a very small hole in the bone. It causes no significant damage to the bone structure. The drill bit is highly hardened and its sharp cutting angle provides a smooth drilling action to prevent the generation of excessive heat. Because the beveled tip makes the hollow drill rotate eccentrically, the diameter of the hole generated by the hollow drill bit is slightly larger than the diameter of the drill bit. This effect, however, allows easy removal of the drill after the injection.
The extended slot in the drill bit allows more uptake of drilling debris without being completely clogged. The alternative open notch design serves the same function as the extended slot hollow drill. The proximal end (opposite end from the distal sharpened tip) of the hollow drill extends outward past the hub and provides an easily identified injection passage for the injection needle.
Before this invention, intraosseous injection techniques in dental anesthesia encountered major difficulties for both patients and dentists. During the early development history of intraosseous injection, reamers or roseheads were used as drill bits. They would cause tremendous bone damage to the patient with greater exposure for potential inflammation and infection. At a later time, a special drill was developed, but the procedure required dentists to find a very small hole under the gum tissue. A potential of mismatching the hole and needle has frustrated many users. Further, because of the limited space and angle accessible to the dentist or operator on the back teeth makes the use much more difficult, therefore, the device is generally limited to the front teeth. The invention described in this document, however, has eliminated all of the above problems. The applicable area expands to the whole mouth, and the small hollow drill will not produce significant bone damage.
This invention is not limited to injecting local anesthetics in dental applications. The invention is broadly usable for injecting a wide range of medications, including antibiotics, and in other medical and veterinary applications.
The features and advantages described in the specification are not all-inclusive. Many additional features and advantages will be apparent to one of ordinary skill in the art in view of the drawings, specifications and claims hereof. Moreover, it should be noted that the language used in the specification has been principally selected for readability and instructional purposes and may not have been selected to delineate or circumscribe the inventive subject matter, or resort to the claims being necessary to determine such inventive subject matter.